Photographic process for the production of colloid relief patterns

ABSTRACT

A photographic process wherein a relief image is formed by means of a photographic material comprising in a recording layer a photosensitive dispersed phase in the form of discrete particles of an intimate mixture of N-vinylcarbazole and carbon tetrabromide in a hardenable hydrophilic colloid medium. The process includes a negative and a positive working mode. Unhardened colloid portions are removed by wash-off. Gelatin is used preferably as hardenable colloid.

United States Patent Hazenbosch et al. 1 Sept. 3, 1974 [54] PHOTOGRAPHIC PROCESS FOR THE 3,046,125 7/1962 Wainer 96/90 R O C O O O O RELIEF 3,476,562 ll/l969 Yamada et al.... 96/90 R 3,503,745 3/1970 Yamada et al.... 96/90 R PATTERNS 3,620,748 11/1971 Fichter 96/90 R [75] Inventors: Edwin Hendrik Hazenbosch, 3,697,276 10/1972 Lewis et a] 96/90 R Mechelen; Albert Lucien Poot, Kontlch both of Belglum Primary ExaminerRonald H. Smith [73] Assignee: Agfa-G t N.V,, M n l, Assistant ExaminerRichard L. Schilling B l i Attorney, Agent, or Firm-William J. Daniel [22] Filed: Sept. 7, 1972 [21] Appl. No.1 286,935 ABSTRACT A photographic process wherein a relief image is [30] Foreign Application Priority D t formed by means of a photographic material compris- Sept. 8 1971 Great Britain 41941/71 ing in a recording layer a photosensitive dispersed phase in the form of discrete particles of an intimate 52 US. (:1. 96/35, 96/351 mixture of N-vinylcarbalole and carbml tetrabromide 51 1m. (:1 G03c 5/00 in a hardenable hydrophilic colloid medium The P [58] Field of Search 96/351 35 36 90 R C655 includes a negative and a Positive mode- Unhardened colloid portions are removed by wash-off. [56] References Cited Gelatin is used preferably as hardenable colloid.

12 Claims, N0 Drawings PHOTOGRAPHIC PROCESS FOR THE PRODUCTION OF COLLOID RELIEF PATTERNS The present invention relates to photographic processes for producing colloid relief patterns.

Photographic systems wherein photosensitive colloid or polymer layers are applied, which are adapted to the duplication of drawings, line and halftone copies, to the reproduction of colour wiring and circuit printing, cartography and colour proofing are generally known.

According to one of such systems dichromated gelatin is used as light-sensitive substance that'on exposure to activating electromagnetic radiation is tanned and on subsequent wash-off yields a relief image of the recorded radiation pattern.

According to another system as described, e. g., in the US. Pat. No. 3,136,638 the formation of a polymer resist is based on the use of normally liquid to solid monomers containing the grouping e.g., acrylamide, methacrylamide, vinyl acetate, methyl methacrylate and acrylonitrile in the presence of a photocatalyst, such as, e.g. iron(III) ammonium citrate, iron(III) oxalate, iron(III) tartrate and the like.

These systems necessitate image-wise exposures to high-intensity radiation emitted by light sources such as a high-intensity carbon arc and this constitutes a decided disadvantage.

In the instant invention relief images are produced by means of a photographic process in which the imagewise exposure is of fairly low intensity.

The recording material applied in the present invention comprises a photosensitive dispersed phase in the form of discrete particles of an intimate mixture of N- vinylcarbazole and carbon tetrabromide in a hydrophilic colloid medium.

A photographic system based on the use of these ingredients has been described in the U.I(. Pat. No. 1,065,548.

The hydrophilic film-forming binder or binder mixture into which the combination of said aromatic N- vinyl compound and photosensitive organic polyhalogen compound is dispersed consists of or mainly contains a water-soluble film-forming colloid containing active hydrogen atoms as are present, e.g., in hydroxyl groups and amino groups. Both qualitative characterization and quantitative determination of active hydrogen can be carried out by the procedure known as the Zerewitinoff active hydrogen determination. Hardenable hydrophilic colloids containing active hydrogen atoms are, e.g., polyvinyl alcohol, polyacrylamide or gelatin, and other film or stratum-forming protein type colloids.

In the present invention best results are obtained with aldehyde-hardenable hydrophilic water-soluble colloids, e.g. gelatin which possess the property of sol-gel transformation.

The present invention provides two modes of operation, a negative working mode, according to which a relief image having reversed image values with respect to the original is formed, and a positive working mode, according to which a relief image having the same image values with respect to the original is obtained.

sure to ultra-violet radiation of an intensity not sufficient to form a printout image. This image-wise exposure results in a decrease of the aptitude of the recording layer to produce in a further exposure of stronger intensity a coloured product in the areas that initially have been struck by light.

It is assumed that by a relatively weak exposure sufficient photoradicals are formed to bring about only the formation of a colourless N-vinyl polymer, whereas the formation of dyestuff salt is inhibited.

In a second step the recording layer is overall exposed to UV. radiation of a higher intensity (more lux.sec) than applied in the image-wise exposure. This results in the formation of a visible image corresponding with the initially non-exposed portions.

In a third step the recording layer is overall heated, preferably in the range of to C, to intensify the colour in the initially non-exposed portions. At the same time the recording layer portions that have been struck by light in the image-wise exposure obtain a decrease in water-permeability and wash-off removability Optionally the heated recording material is subsequently overall exposed to very intensive ultra-violet radiation. This exposure results in the colouration of the initially image-wise exposed portions of the recording layer. When the recording layer incorporates colouring matter e.g. already applied in the coating stage in the form of dyes or coloured pigments said very intensive ultra-violet radiation exposure is not necessary for obtaining a coloured negative relief image in thesubsequent wash-off step.

In the final step the recording layer portions, which correspond with the areas that initially have not been struck by the weak radiation, are washed off selectively by means of an aqueous liquid, e.g., tap water having a temperature in the range of 2050C. As a result of the whole procedure a coloured negative relief image is obtained.

In the positive working mode .of the invention wherein the same recording layer is used as described in the negative working embodiment, the recording layer in a first step is given an image-wise exposure with ultra-violet radiation of an intensity sufficient to produce'a visible print-out colour image.

In a second step, the recording layer is overall heated thereby effecting an intensification of the colour image in the initially exposed portions and a reduction of the water-permeability and wash-off removability of the portions of the recording layer that have not been struck image-wise by U.V.-radiation.

In a third step the recording layer is subjected to a very intensive overall exposure to ultra-violet radiation effecting a colouration in the portions of the recording layer that initially have not been struck by said radiation.

In the fin'al step the recording layer portions that initially have been struck by the light of the image-wise exposure are removed by an aqueous wash-off treatment so that a positive relief colour image of the original remains.

In the negative working mode as well as in the positive working mode the recording layer composition contains the N-vinylcarbazole and carbon tetrabromide in a preferred molar range of 40:60 to 75:25.

The hardenable hydrophilic colloid binder is present for preferably 60 parts by weight with respect to 100 parts by weight of the mixture of N-vinylcarbazole and carbon tetrabromide.

The above described photosensitive composition is inherently sensitive to near ultraviolet radiation and to blue light.

It is possible, however, to extend the spectral sensitivity of the present photosensitive composition by means of spectral sensitizing agents to the visible light range and even to infra-red. Suitable spectral sensitizing agents are compounds that have the property of absorbing electromagnetic energy and that can convert such energy and transfer it through an active contact with a phototransformable substance to said substance. A survey of suitable sensitizing agents for the photosensitive compositions used according to the present invention is given in the French Patent Specification 1,574,740 and the US. Pat. No. 3,503,745.

Preference is given to the use of so-called spectrally sensitizing dye bases more particularly those of the styryl and azastyryl type, e.g. 4-(p-dimethylaminostyryl)-quinoline and Z-(p-dimethylaminostyryl)- quinoline.

These dye bases yield dyes that are good red sensitizers for the photopolymerization of aromatic N-vinyl compounds (see Yamada et al.; Camera Speed Photopolymerization System Part II, Dye-Sensitization and Latensification in the Basic Photopolymerization Emulsion Preprints SPSE Congress Los Angeles May 12-16, 1969).

The molar ratio of dye base to photosensitive carbon tetrabromide is preferably in the range of 0.0001 to 0.01.

By the presence in the recording layer of spectral sensitizing agents such as the styryl dye bases coloured negative relief images can be produced through the following steps:

the photosensitive recording layer containing the dye base is given a weak image-wise exposure to visible light,

2. the recording layer is overall exposed to visible light of an intensity high enough to produce a colouration in the initially non-exposed areas of the recording layer,

3. the photosensitive composition is overall heated, preferably between a temperature of ll50C, to intensify the colour in the initially non-exposed areas and to effect a selective decrease in water-permeability of the initially image-wise exposed areas,

4. the photosensitive composition is overall exposed to intensive ultra-violet radiation, resulting in a colouration of the initially image-wise exposed areas of the recording layer, and

5. the areas of the recording layer that have not been exposed initially are removed by an aqueous wash-off treatment.

By the use of a spectrally sensitized recording layer the already described process for forming positive relief images may proceed with an image-wise exposure to visible light instead of an image-wise exposure to ultra-violet radiation.

According to a preferred embodiment for preparing the recording material the carbon tetrabromide before its incorporation into the coating composition is first dissolved in a high-boiling organic liquid, e.g. ethylene glycol monomethyl ether, and in that state dispersed in the hydrophilic colloid medium, in which it comes in intimate contact with the aromatic N-vinyl compound.

The spectral sensitizing agent, at least if one is applied, is preferably incorporated into the recording layer composition in the fonn of a solution in a solvent that is miscible with water, so that it becomes very homogeneously distributed throughout the hydrophilic colloid and can come in intimate contact with the complex formed by the polyhalogen and N-vinyl compound.

The photosensitive coating composition can be applied to any type of support known from the photographic art, e. g. a transparent resin support and a transparent or opaque paper support. Optionally the support is provided with a subbing layer known in the art for hydrophilic colloid layers such as gelatin-containing layers.

The light sources used for exposure in the present invention may be any light source of the commercial type emitting in the wavelength range indicated in the preceding exposure modes.

The heating step before the final overall ultraviolet exposure may proceed with the common means suited for that purpose, e.g. heated rollers, hot glazing plate, hot air current and the like.

The wash-off treatment of the water-permeable colloid portions may proceed advantageously with running water (tap water at a temperature of 20'60C) with the application of some mechanical friction.

The present invention is further illustrated by the following examples.

The percentages and ratios are by weight unless otherwise indicated.

Example 1 Preparation of the recording material A photographic paper support was covered with a subbing layer of the following composition:

Gelatin 30 g. 11.7% solution of saponine in a mixture of ethanol/water (1:4 5 ml.

by volum 5% aqueous solution of a 50:50 mixture of the wetting agents having the following formulae:

Water to 1,000 g.

solution of the wetting agent TERGITOL 4 (7-ethyl-2- methyl-4-undecanol ester of sodium hydrogen sulphate marketed by Union Carbide and Carbon, New York, USA.) and 50 g of N-vinylcarbazole added in a high speed mixer. After intensive mixing for 5 min. a solution of 50 g of carbon tetrabromide in 30 ml of ethylene glycol monomethyl ether was added together with 10 m1 of a percent aqueous solution of a naphthalene sulphonate as a dispersing agent.

The high speed mixing was continued for 2 min., during which period of time the temperature reached 72C.

The dispersion obtained was cooled down to 40C and then mixed by low speed stirring with the following ingredients:

tricresyl phosphate (plasticizin g After a deaeration period of 1 hour the recording layer composition was coated on the subbing layer at the indicated ratio and dried.

Recording and Processing The light-sensitive recording layer held in contact with a transparent line original was exposed for 2 sec. through said original with a 1,000 W ultra-violet lamp held at a distance of 10 cm. A negative blue-print-out image was formed.

The image-wise exposed recording material was heated for 10 sec. at 140C by keeping it on a hot glazing plate.

The heated material was then exposed to ultra-violet radiation with the same radiation source as applied in the image-wise exposure but now for 10 sec.

The thus exposed recording layer was then held under a jet of water having a temperature of 30C whereby the initially image-wise exposed portions of the recording layer were removed and a black positive copy of the original on a white image background was obtained.

Example 2 The recording material was the same as that of Example 1.

Recording and Processing The photosensitive recording layer held in contact with a transparent line original was exposed for 15 sec. through said original with a 1,000 W incandescent lamp held at a distance of 5 cm.

The image-wise exposed recording material was heated for 15 sec. at 140C by conveying it between a pair of heated rollers.

The heated recording material was then overall exposed for 10 sec to an ultraviolet radiation source of 1,000 W held at a distance of 10 cm.

A wash-off treatment with running water having a temperature of 40C was applied, whereby a black positive copy of the original on a white image background was obtained.

Example 3 The composition of the recording material was the same as that described in Example 1.

Recording and Processing The light-sensitive recording layer was contactexposed for 3 see through a positive silver image line transparency in a THERMOFAX (type Secretary) copying apparatus of Minnesota Mining and Manufacturing Co., St. Paul, Minn., USA.

The recording layer that was image-wise exposed to infrared radiation was overall heated for 10 sec. at 140C by contacting it with a hot glazing plate.

The overall heating was followed by an overall exposure of 10 sec. to ultra-violet radiation with a 1000 W ultra-violet lamp held at a distance of 10 cm.

The thus exposed recording layer was then treated with a jet of tap water having a temperature of 30C whereby the initially image-wise exposed portions of the recording layer were removed and a black positive copy of the original on a white image background was obtained.

Example 4 The recording material was the same as that described in Example 1.

Recording and Processing The photosensitive recording layer while being in contact with a transparent line original was exposed for 0.1 sec. with a W high pressure mercury vapour ultra-violet lamp (type HPR PhilipsGloeilampenfabrieken, Eindhoven, Netherlands).

The image-wise exposure was followed by an overall exposure for 2 sec. with the same light source.

The thus exposed recording material was overall heated for 10 sec. at C by conveying it over a heated drum.

The heated recording material was then overall exposed for 10 sec. with an ultra-violet lamp of 1000 W placed at a distance of 10 cm.

Thereupon the thus exposed recording layer was placed in a stream of running tap water (temperature 20C), whereby a black copy having reversed image values with respect to the original was obtained.

Example 5 The recording material was the same as that described in Example 1. Recording and Processing The photosensitive recording layer while being in contact with a transparent line original was exposed for 1 sec. with a 1000 W incandescent lamp placed at a distance of 5 cm.

The image-wise exposed recording layer was then overall exposed with the same incandescent lamp for 5 sec. The further processing was the same as that described in Example 4. The obtained result was the same as that described in Example 4.

Example 6 The recording material was the same as that described in Example 1. Recording and Processing The photosensitive recording layer was exposed in an enlarging apparatus (type reader-printer)-through a transparent microfilm image of a line original. The exposure lasted 10 sec. and was effected with a W incandescent lamp placed at a distance of 30 cm and emitting 1000 lux.

The enlargement was 10 times.

The image-wise exposed recording material was overall exposed for sec with an incandescent lamp of lOOOW placed at a distance of 30 cm or overall exposed for 1 sec. with an ultra-violet high pressure mercury vapour lamp of 125 W type HPR.

The thus exposed recording material was overall heated at 140C for sec. on a hot glazing plate.

The heated recording material was overall exposed for 10 sec. with an ultra-violet source of 1000 W held at a distance of 10 cm.

A wash-off treatment with running water having a temperature of 50C was applied, whereby a black copy enlarged 10 times and having reversed image values with respect to the microfilm original was obtained.

Example 7 The recording material was the same as that described in Example 1.

Recording and Processing The recording material was exposed reflectographically for 1 sec. to infra-red radiation in a thermographic copier THERMOFAX type secretary copying apparatus using a line original (printed text on opaque paper base).

The recording material was then overall exposed for 2 sec. with an ultra-violet lamp of 125 W placed at a distance of 30 cm or overall exposed for 3 sec. with an incandescent lamp of 1000 W placed at a distance of 5 cm from the recording layer.

The thus overall exposed recording material was then overall heated for 10 sec. at 140C on a hot glazing plate.

The heated recording material was then overall exposed for 10 sec. with an ultra-violet lamp of 1000 W.

A wash-off treatment in running water of 30C yielded a negative reflex copy (mirror image) suited for yielding positive direct copies of the initially used original in contact-printing e.g., on silver halide emulsion paper. e.g., Example 8 The recording material was the same as that described in Example 1.

Recording and Processing The reflectographic exposure was the same as that described in Example 7 with the difference, however, that it lasted 3 sec and yielded a visible print-out image.

The recording material containing the print-out image was overall heated for 10 sec. at 140C on a hot glazing plate.

The further processing was the same as in Example 7 but now a positive reflex copy (mirror image) was obtained.

Example 9 Preparation of the recording material An unsubbed polyethylene terephthalate film was first covered with a precoat at a ratio of 33 g per sq.m with the following composition:

Chloral hydrate 100 g resorcinol 30 g 30% aqueous dispersion of colloidal silica (average particle size 25 mp.) 33 ml water 552 ml ethanol 400 ml 5% aqueous solution of heptadecyl- -Continued benzimidazole disodiumsulphonate as wetting agent The resulting precoat was covered with a subbing layer and a photosensitive layer as described in Example 1.

Recording and Processing The photosensitive recording layer was contactexposed for 5 sec. through a positive line transparency with a 1000 W ultra-violet lamp.

The image-wise exposed recording material was overall heated for 3 sec. at C by conveying it between hot rollers.

The heated recording material was overall exposed for 10 sec. to the ultra-violet radiation of a 1000 W lamp placed at a distance of 10 cm.

A wash-off treatment in running water of 30C yielded a black-positive copy of the original. The copy was suited for use as an intermediate original in diamtype copying.

Example 10 The recording material was the same as that described in Example 9.

Recording and Processing The photosensitive recording layer was exposed in an enlarging apparatus (type reader-printer) through a transparent microfilm image of a line original. The exposure lasted 10 sec. and was effected with a 150 W incandescent lamp emitting 1000 lux. The enlargement was 10 times.

The image-wise exposed recording material was overall exposed for 5 sec. with an incandescent lamp of 1000 W or for 1 sec. with an ultraviolet lamp of W (type HPR).

The thus overall exposed recording material was then overall heated for 3 sec. at 90C on a hot glazing plate.

The overall-heated recording material was then overall exposed for 10 sec. with an ultra-violet lamp of 1000 W.

A wash-off treatment with running water of 30C resulted in the production of a 10 times enlarged copy having reversed image values with respect to the microfilm original.

What we claim is:

l. A photographic process for forming a relief image in a photographic material including a recording layer comprising a photosensitive dispersed phase in the form of discrete particles of an intimate mixture of N- vinylcarbazole and carbon tetrabromide in a hardenable hydrophilic colloid medium, said colloid containing active hydrogen atoms, by

A. a negative mode for producing a relief image having reversed image values with respect to an original and comprising the following steps:

1. imagewise exposing said layer to radiation to which said layer is sensitive of an intensity not sufficient to form a print-out image directly,

2. uniformly exposing said layer to radiation to which said layer is sensitive of a higher intensity than used in the imagewise exposure and sufficiently strong to bring about the formation of a visible image corresponding with the initially non-exposed portions,

3. uniformly heating said layer to intensity the color in the initially non-exposed portions, and to bring about a decrease in water-permeability and wash-off removability in the initially exposed recording layer portions, and

4. selectively washing off the recording layer portions which correspond with the initially nonexposed areas by means of an aqueous liquid; or

B. a positive mode for producing a relief image having the same image values as an original to be reproduced and comprising the following steps:

1. imagewise exposing said layer to radiation to which said layer is sensitive of an intensity sufficient to produce a visible print-out color image,

2. uniformly heating said layer to effect an intensification of the color image in the initially exposed regions and a reduction of the water-permeability and wash-off removability of the non-exposed layer regions,

3. uniformly exposing said layer to radiation to which said layer is sensitive of an intensity sufficient to effect a coloration in the initially nonexposed layer regions, and

4. washing off the initially exposed recording layer regions by an aqueous wash-off treatment.

2. A process according to claim 1, wherein the hydrophilic hardenable colloid is a protein.

3. A process according to claim 2, wherein the colloid is gelatin.

4. A process according to claim 1, wherein the recording layer composition contains N-vinyl-carbazole and carbon tetrabromide in a molar range of 40:60 to 75:25.

5. A process according to claim 1, wherein the recording layer contains 60 parts by weight of hardenable hydrophilic colloid binder with respect to parts by weight of the mixture of N-vinylcarbazole and carbon tetrabromide.

6. A process according to claim 1 wherein said layer in the two first steps of said negative mode is exposed to visible light or infrared radiation and the photosensitive dispersed phase is spectrally sensitized to visible light and/or infrared radiation by means of a styryl dye base.

7. A process according to claim 1 wherein in the first steps of the positive mode said layer is exposed to visible light or infrared radiation and the photosensitive dispersed phase is spectrally sensitized to visible light and/or infrared radiation by means of a styryl dye base.

8. A process according to claim 6, wherein 4-(pdimethylaminostyryl)-quinoline or 2-(p-dimethylaminostyryl)-quinoline is used as said styryl dye base.

9. A process according to claim 7, wherein 4-(pdimethylaminostyryl)quinoline or 2-(p-dimethylaminostyryl)-quinoline is used as said styryl dye base.

10. A process according to claim 1, wherein the recording layer contains coloured pigments or dyes.

11. The process of claim 1 wherein said radiation to which said layer is sensitive in said steps (1) and (2) of said negative mode or steps (1) and (3) of said positive mode is ultraviolet radiation.

12. The process of claim 1 wherein said negative mode (A) includes between said uniform heating and selective washing off steps the additional step of uniformly exposing the recording layer to strong UV.- radiation to effect coloration of the initially exposed layer regions. 

2. A process according to claim 1, wherein the hydrophilic hardenable colloid is a protein.
 2. uniformly exposing said layer to radiation to which said layer is sensitive of a higher intensity than used in the imagewise exposure and sufficiently strong to bring about the formation of a visible image corresponding with the initially non-exposed portions,
 2. uniformly heating said layer to effect an intensification of the color image in the initially exposed regions and a reduction of the water-permeability and wash-off removability of the non-exposed layer regions,
 3. uniformly exposing said layer to radiation to which said layer is sensitive of an intensity sufficient to effect a coloration in the initially non-exposed layer regions, and
 3. uniformly heating said layer to intensity the color in the initially non-exposed portions, and to bring about a decrease in water-permeability and wash-off removability in the initially exposed recording layer portions, and
 3. A process according to claim 2, wherein the colloid is gelatin.
 4. A process according to claim 1, wherein the recording layer composition contains N-vinyl-carbazole and carbon tetrabromide in a molar range of 40:60 to 75:25.
 4. selectively washing off the recording layer portions which correspond with the initially non-exposed areas by means of an aqueous liquid; or B. a positive mode for producing a relief image having the same image values as an original to be reproduced and comprising the following steps:
 4. washing off the initially exposed recording layer regions by an aqueous wash-off treatment.
 5. A process according to claim 1, wherein the recording layer contains 60 parts by weight of hardenable hydrophilic colloid binder with respect to 100 parts by weight of the mixture of N-vinylcarbazole and carbon tetrabromide.
 6. A process according to claim 1 wherein said layer in the two first steps of said negative mode is exposed to visible light or infrared radiation and the photosensitive dispersed phase is spectrally sensitized to visible light and/or infrared radiation by means of a styryl dye base.
 7. A process according to claim 1 wherein in the first steps of the positive mode said layer is exposed to visible light or infrared radiation and the photosensitive dispersed phase is spectrally sensitized to visible light and/or infrared radiation by means of a styryl dye base.
 8. A process according to claim 6, wherein 4-(p-dimethylaminostyryl)-quinoline or 2-(p-dimethylaminostyryl)-quinoline is used as said styryl dye base.
 9. A process according to claim 7, wherein 4-(p-dimethylaminostyryl)quinoline or 2-(p-dimethylaminostyryl)-quinoline is used as said styryl dye base.
 10. A process according to claim 1, wherein the recording layer contains coloured pigments or dyes.
 11. The process of claim 1 wherein said radiation to which said layer is sensitiVe in said steps (1) and (2) of said negative mode or steps (1) and (3) of said positive mode is ultraviolet radiation.
 12. The process of claim 1 wherein said negative mode (A) includes between said uniform heating and selective washing off steps the additional step of uniformly exposing the recording layer to strong U.V.-radiation to effect coloration of the initially exposed layer regions. 